Display devices, such as liquid crystal display devices, are used in order to display various information. As shown in FIGS. 37 and 40, for example, a display device includes a gate bus line, a source bus line, an auxiliary capacitance line, a pixel electrode, and an opposed electrode. The pixel electrode is provided within a region surrounded by the gate bus line and the source bus line and provided so as to overlap with the source bus line, in order to receive a data signal from the source bus line. The opposed electrode is opposed to the pixel electrode.
Examples of such display devices are disclosed, for example, in U.S. Pat. No. 5,946,058 (date of patent: Aug. 31, 1999) and United States Patent Publication No. 2002/0057391A1 (date of publication: May 16, 2002).
According to the conventional arrangement, as shown in FIG. 39, a source-drain parasitic capacitance (hereinafter occasionally referred to by abbreviation “Csd”) is formed at each position where a pixel electrode 21 and a source bus line 18 overlap. The source-drain parasitic capacitance is undesirable, because it can cause vertical crosstalk and flicker. In FIG. 39, the black arrow indicates application of data signal.
According to the conventional arrangement, as shown in FIG. 42, a source-drain parasitic capacitance (hereinafter occasionally referred to by abbreviation “Csd”) is formed at each position where a pixel electrode and a source bus line overlap. Through this capacitance, the potential of the pixel is attracted when the potential of the source bus line fluctuates. Since the amount of attracted pixel potential is different with respect to each horizontal line, the difference in the amount of attracted pixel potential appears as a difference in luminance (=horizontal stripes). As a result, even display cannot be attained. In FIG. 42, the black arrow indicates application of data signal, and the white arrow indicates a potential attraction effect with respect to G(green)-pixels.
The following specifically discusses how the horizontal stripes are generated.
FIG. 42 is a schematic diagram illustrating source bus lines, pixel electrodes, and source-drain parasitic capacitances of a delta arrangement display panel.
Here, attention is paid to a G-pixel, for example. As shown in FIG. 42, the G-pixel is adjacent to a source bus line for a G-signal and a source bus line for an R-signal or a B-signal. Whether the source bus line adjacent to the G-pixel is R or B is alternated with respect to each horizontal line. That is, if a G-pixel in one horizontal line is sandwiched between an R-line and a G-line, a G-pixel in an adjacent horizontal line is sandwiched between a G-line and a B-line.
Structurally, a pixel electrode and a source bus line overlap at a certain position, with an insulating film in between. Therefore, there is a source-drain parasitic capacitance. Suppose that a capacitance between a pixel electrode and a source bus line that drives the pixel (in this case, a capacitance with a G-line) is Csd1, and a capacitance between a pixel electrode and a source bus line that does not drive the pixel (in this case, a capacitance with an R-line or a B-line) is Csd2. The potential of the G-pixel is attracted through these capacitances when the potentials of the source bus lines fluctuate. The G-pixel sandwiched between an R-line and a G-line is attracted to the R-line and the G-line, and the G-pixel sandwiched between a G-line and a B-line is attracted to the G-line and the B-line. The attraction by the G-line is the same in both cases. On the other hand, the attraction by the R-line and the attraction by the B-line are not always equal. Therefore, the voltage applied to the liquid crystal of the G-pixel is different with respect to each horizontal line. As a result, stripes (horizontal stripes) are formed by horizontal lines when an intermediate gradation is displayed by the G-pixel. This phenomenon occurs not only with respect to a green pixel G, but also with respect to a red pixel R and a blue pixel B.
For example, horizontal stripes appear saliently when R displays white, G displays an intermediate color, and B displays black.